The long term objectives are to determine the molecular mechanisms underlying the regulation of tissue-specific gene expression in the parotid gland. We have found that two glucose transporter (GLUT) isoforms (GLUT 1 and GLUT 2) are expressed in the rat parotid gland. Although GLUT 1 is expressed in many eukaryotic cells, GLUT 2 expression is confined to the liver, certain cells in kidney and intestine, and beta-cells of the pancreatic islets, where it is presumed to be involved in the regulation of insulin secretion. Insulin-like peptides are also produced in some isolated cells and ductal cells of the rat parotid gland. If GLUT 2 is expressed in these cells that produce insulin-like peptides, the GLUT may serve as an important regulatory protein in parotid gland cells, especially in altered metabolic states involving glucose. Prior to initiating studies to determine the role of GLUTs in parotid gland functions, the specific cells that express these transporters must be identified. Therefore, the specific aim of this proposal is to determine the specific sites of GLUT1 and GLUT2 gene expression in rat parotid glands by localizing their respective a) gene transcripts by in situ hybridization, and b) protein products by immunocytochemical techniques.